Revert "bpo-39087: Add _PyUnicode_GetUTF8Buffer()" (GH-18985)

* Revert "bpo-39087: Add _PyUnicode_GetUTF8Buffer() (GH-17659)"

This reverts commit c7ad974d341d3edb6b9d2a2dcae4d3d4794ada6b.

* Update unicodeobject.h
5 files changed